Until the early 19th century, visiting Italy was the sine qua non of artistic formation, whether you came from France (Ingres, Corot), Spain (Goya), England (Turner) or Germany (Schinkel). It was only when art’s unbroken line back to quattrocento classicism started to falter that the theorists moved in. Jacob Burckhardt in his 1860 book The Civilization of the Renaissance in Italy was the first art historian to use and popularise the term “Renaissance”. Since then, the epoch has been all things to all men.

Burckhardt, whose book remains a template, saw the Renaissance as the dawn of the spirit of individuality and of modernity. In the following years, Walter Pater in The Renaissance interpreted it through the prism of fin-de-siècle aestheticism; Freud psychoanalysed Leonardo; in the 1930s, Marxist critic Meyer Schapiro pinpointed the emergence of capitalism in the period. What we do with the Renaissance, then, defines how we see ourselves, which is why this current crop of histories is so mordantly entertaining and illuminating. Holding up a mirror to the cut-throat competition, personality cults and public display of the 21st-century art world, all are portraits of creative rivalry and power play which will be recognisable to anyone observing, to take one example, the recent face-off between Antony Gormley and Anish Kapoor over London’s Olympic commission.

Jonathan Jones’s The Lost Battles takes its spark from a line in Vasari’s The Lives of the Artists on the animosity between Leonardo and Michelangelo, and in particular an anecdote which recorded a spat between the pair on the street outside the Palazzo Spini. This was probably rooted in disputes about the merits of sculpture – whose ancient models Michelangelo was reinvigorating with a new, personal expressiveness – and painting, favoured by Leonardo whose work unsettled early viewers with its breathtaking naturalism: those who first saw the Mona Lisa “remembered how in the pit of the woman’s throat, if you looked long enough, you’d see the beating of the pulse”.

Jones answers Vasari’s picture of high-cultured Florence with a depiction of a vendetta-ridden city where public torture was as likely a mass attraction as the unveiling of David, revolts and invasions were constant dreads, and patronage went hand in hand with paranoia. In these fraught times, “for everything that is built, every beauty that is nurtured, there is a destructive warrior waiting in the wings”. In 1503, republican state adviser Niccolò Machiavelli came up with a patriotic but brutish idea: to set Leonardo and Michelangelo against one another, commissioning a monumental mural celebrating Florentine victories from each artist.

Did creative rivalry spur or stifle them? We shall never know, because there are two lost battles here: the personal feud which Jones reconstructs, with almost fictional liberty (“the insults flew thick and furious”, “these two titanic talents were ... working heroically – daring the dark, braving the heights”), and the works themselves: Leonardo’s “Battle of Anghiari” and Michelangelo’s “Battle of Cascina”. Neither were finished, only a few sketches survive; some for Cascina are on display at the British Museum’s superb Italian Renaissance Drawings exhibition. Jones points out that in choosing Cascina, the bloody battle fought in 1364 between soldiers from Florence and Pisa, Michelangelo seized “a rare opportunity to portray an army with its clothes off”, assembling a battalion of twisting, stretching nude soldiers, more appropriately described as “The Bathers”.

These are lively observations, but by no stretch is this episode “the artistic duel that defined the Renaissance”. Rather, it is a dummy which Jones, a Guardian art critic, clothes with his own imaginative wardrobe. This is sometimes arresting: the contrast between foppish Leonardo’s rose-pink robes, for example, and Michelangelo’s dusty tunic. But often it is bombastic and longwinded: “each pen stroke aches with wonder”; “when he carved his David ... Michelangelo revealed what art can be”; “Leonardo spewed out a great whirl of chalk ...out of weirdness he discovers harmony.”

As interpretation, this is unenlightening; so is the over-simple dichotomy that “for Michelangelo, life is spirit. For Leonardo, it is biology”. Yet Jones is surely right to underline the religious-political context. When both artists left Florence, it was symbolic that the fervent younger man found favour in Rome, while the rationalist older one fled to France: “Michelangelo was the prophet of an art which could renew Catholic Italy. Leonardo heard his message, and emigrated.”

In secular, republican Venice, they did things differently, but art was still inextricably tied to religion and power. In her intriguing Becoming Venetian, Blake de Maria, a professor of art history at Santa Clara University, follows the fortunes of immigrant families who rose to citizen status, tracing how the art they commissioned bought acceptance, consolidated status and asserted their Catholic faith.

This fabulously illustrated, original contribution to the literature celebrating Venice opens with Vittore Carpaccio’s “Miracle of the Relic of the True Cross on the Rialto Bridge” (1494), now at the Accademia: a virtuoso panorama of the buzzing activity around early modern Europe’s “premier mercantile entrepot”, the Rialto market, including many foreign traders and the flamboyant central figure of an African gondolier. The painting reflects Venice’s identity as the New York of the Renaissance: fast-moving, showy, a melting pot of nationalities, deriving energy and colour from its ambitious new arrivals.

Artists here had to be cunning as well as talented. In 1564, judges for the competition to decorate the hall of the Scuola Grande di San Rocco, run by a confraternity of arriviste merchants, turned up to find sketches by Veronese, Salviati and others – and a Tintoretto painting already finished and in situ. “Designs and models should always be done in this fashion, so as to deceive no one,” explained the artist, “and ... if they did not want to pay him for the work and for his labour, he would donate these”. The painting, “St Roch in Glory”, was accepted as a gift – but the next year the scuola paid for a magnificent “Crucifixion”, and by 1577 Tintoretto had received 2,000 ducats of San Rocco commissions.

De Maria speculates that Tintoretto was welcomed as a compromise candidate, resolving disagreements between the confraternity leaders. The d’Anna family, originally from Brabant, had close ties with Titian. They commissioned his great “Ecce Homo”, depicting the family as religious pilgrims to showcase their Catholic allegiance – lest their Netherlandish roots raised suspicions of Protestantism. The Cuccina cloth merchants favoured Veronese. Few works more perfectly match painter and patron than his magisterial “Cuccina Family Cycle”, featuring Alvise Cuccina, his wife and children dressed in silks and satins – Alvise in orange and yellow brocade as host in “The Wedding Feast at Cana”, his sons in black and white striped costumes as visitors to the “Madonna and Child” – whose sumptuous textural rendering advertises the wares on sale at the Cuccina palazzo. This cycle became renowned – Charles I offered 32,000 scudi for it. Alvise’s grandson, Antonio Cuccina, eventually swapped the paintings for a villa carrying a hereditary title: thus Veronese’s visual glorification of the family became the very object that actually bestowed noble status upon it.

While Titian and Veronese were dignifying Venice’s grandees, a new autocratic Medici regime in 1530s Florence demanded a new court painter. Agnolo Bronzino’s haughty state portraits, cool as marble, defined the genre across Europe for a century. Then tastes changed and Bronzino fell into obscurity – he remains hardly known. With a landmark show at Venice’s Palazzo Pitti opening in the autumn, Florence has designated 2010 “Bronzino Year”. New York’s Metropolitan Museum contributed with a drawings exhibition this spring and the seminal, lavish The Drawings of Bronzino – at once biography, art history and scholarly catalogue.

Born a butcher’s son in 1503, Bronzino grew up in awe of his Florentine predecessors, especially Michelangelo’s sculptural perfection. His own statuesque, inscrutable Medici portraits such as “Eleonora di Toledo with her son Giovanni”, and mythological scenes including the National Gallery’s porcelain-sexy shocker “An Allegory with Venus and Cupid”, are showcases of chilly artifice. Long seen as mannerist – the product of despotic patrons prizing style and a gloss of civility to mask the reality of brutal power – the paintings here receive a more nuanced reading by the revelatory context of Bronzino’s drawings.

These have an archaic, idealising quality, and soft luminosity. We see the recurring motif of an upturned child’s head with heavy eyelids, large rounded eyes, pronounced curve of the lips and shock of curls – a model for angels, putti, infant St John or Christ; the refined, beautiful youth with a lute thought to be a “Head of Dante”; the delicate, wistful contours and half-smile of “Young Israelite Woman”. How different, in immediacy and darting energy, these works are from Bronzino’s static formal portraits, with their starkly intimidating Florentine architectural backcloths. The contrast animates this delightful volume, giving insight into Bronzino’s working methods and the compromises of personality versus patronage.

From forgotten Bronzino, Jones’s minor-key anecdote, Venice’s overlooked patron – all these books approach the Renaissance tangentially: the period has been so mined that few other options are open to 21st-century historians. How, then, to remain objective when there surfaces after half a millennium what Martin Kemp, Oxford emeritus professor of art history, admits is “that rarest of rare things” – an unknown Leonardo portrait featuring a historically significant subject?

La Bella Principessa argues that a colour chalk drawing on vellum of an attractive teenage girl dressed demurely in 1490s Milanese court attire, sold as a late 19th-century German imitation for £12,000 in 2007, is in fact an original portrait of Bianca Sforza, illegitimate daughter of Leonardo’s patron Duke Ludovico Sforza. Kemp details the art-historical case, ranging from Leonardo’s left-handed cross-hatching to the character of the drapery. Pascal Cotte adds scientific documentation, such as vellum carbon-dating.

Both offer complex, dry though far from conclusive evidence, with not enough complementary images. What better animates the narrative is Kemp’s intense speculation about Bianca, her mesmerising presence at her father’s court and her tragic early death.

Meanwhile, this “star portrait of a stellar sitter” has just been unveiled at a Gothenburg museum. Gothenburg? Why not at the British Museum’s current show, or the Louvre, home to Leonardo’s most famous enigmatic sitter? The answer is that neither will have it. And here are just two caveats which set alarm bells ringing. First, why coloured chalk and vellum? Leonardo used neither; he drew on paper, there are no known works by him on vellum. But vellum is more durable – hence more easily available to later artists than 15th-century paper. Second, if Bianca is the subject, why are there no references to so high profile a commission in Vasari, or in Sforza family records?

The Italian Renaissance is one of the greatest historical constructs of all time. This drawing probably dates from Germany in the years after Burckhardt defined it to an enthralled young generation. Kemp is a scholar, susceptible as historians always have been, to fantasies about the period. In that sense, La Bella Principessa, shot through with yearning for fresh examples of quattrocento youth and beauty, is true to itself. We each remake the Renaissance in our own image.